Business Combinations (Narrative) (Details) (USD $)	3 Months Ended		12 Months Ended	3 Months Ended
	Mar. 31, 2013 operating_location	Mar. 31, 2012	Dec. 31, 2012	Mar. 31, 2013 Circle Bancorp [Member] operating_location	Nov. 14, 2012 Circle Bancorp [Member]
Business Acquisition [Line Items]
Aggregate cash paid to aquire entity				$ 24,900,000	$ 24,860,000
Number of locations in operation	201			6
Goodwill				12,500,000	12,545,000
Revenues				5,000,000
Non-interest expense	85,762,000	87,696,000		2,700,000
Net income (loss)	23,361,000	25,503,000	101,891,000	1,300,000
Merger related expenses	$ 1,531,000	$ 100,000		$ 891,000